What is Business Logic Abuse?

Business logic abuse is a common attack technique directed at web and mobile applications as well as their APIs. These attacks appear as valid interactions because the attacker is exploiting intended app or API functionality, which also enables them to bypass traditional security solutions without detection. These attacks can be automated and massively scaled through bots, potentially leading to data loss, theft, or fraud.

What are Business Logic Vulnerabilities?

The business logic of applications and APIs defines and enforces a set of rules and limitations during application design and functionality development. This logic attempts to ensure that users – or bots acting as users – can only use the app or API in a manner in which it was designed and cannot perform activities that can negatively impact the application or infrastructure.

Applications and APIs empowered with even the best authentication and controls, functioning seamlessly and as expected, can have design and process flaws exploitable by attackers. In addition, developers can’t always predict how the users will interact with the application, leaving the door open for attackers to use behavioral flaws to detrimental consequences.

A business logic vulnerability results from business logic errors in the application or API, which are then exploited by criminals to launch business logic abuse attacks, appearing to be legitimate or even syntactically correct. It is this perceived legitimacy that enables these attacks to pass through existing security infrastructure without detection.

Application and API testing is critical to uncover these vulnerabilities, but legacy testing tools such as Dynamic Application Security Testing (DAST) cannot discover all logical flaws. As previously mentioned, existing security infrastructure might not be able to prevent such attacks because of the apparent legitimacy of these attacks.

Business Logic Abuse Examples

Business logic attacks can surface anywhere a user or automated tool can interact with a given application or API. Attackers will attempt to manipulate the business logic of the application into producing the results the criminal desires. Some examples of business logic abuse include:

• Access control – attackers may manipulate URLs, session tokens, cookies, or hidden fields to gain advanced privileges and access sensitive data or functionality.
• Input validation – bots may attempt to repeatedly sign up, login, or execute purchases in order to validate credentials, access unauthorized data, or commit fraud.
• Session management – flaws in session tokens or poor handling of session data could lead to hijacked sessions and privilege escalation.
• Business constraint exploitation – attackers may try to bypass built-in constraints to business logic by reviewing points of entry such as form fields and coming up with inputs that the developers may not have planned for. For example, bypassing the purchasing workflow could allow an attacker to purchase a product without paying.

These examples could occur in virtually any online business website. In addition, the larger and more sophisticated a website is, the more likely it is to have business logic flaws simply due to the complexities of the site.

Impacts of Business Logic Abuse

Business logic abuse is a critical security challenge because even well-coded apps and APIs can fall prey to such attacks. These APIs might be hardened against OWASP API Security Top 10 threats and the organization may have granular visibility into their APIs and usage, but they still could be susceptible to business logic abuse. Attackers looking for ingress points into apps and APIs zero in on business logic as the weakest link in an otherwise bug-free app or API and will leverage bots to automate massively scale their processes and tactics. Impacts of business logic abuse include:

• Increased infrastructure costs incurred handling the increased traffic volume resulting from bot attacks
• Loss of revenue from stolen goods
• Loss of user confidence due to missing out on limited quantity sales or stolen loyalty points
• Increased personnel costs resulting from the additional headcount required for cybersecurity monitoring and response

Preventing Business Logic Abuse Attacks

Business logic abuse attacks are very different from standard vulnerabilities and are much harder to detect. What’s needed is a solution that can see all the traffic to a given application or API and is able to detect anomalies based on multiple behavioral-based criteria. Solutions that require per-app instrumentation through JavaScript or SDKs will necessarily not cover all applications, and attackers are too savvy to be detected based on any single criterion. The Cequence Unified API Protection platform requires no app instrumentation and utilizes multi-dimensional machine learning to detect malicious intent. Cequence incorporates four pillars of threat detection, including tools, infrastructure, credentials, and behavior to accurately identify business logic abuse attacks and prevent them natively.

We’d love to talk to you about how Cequence can help your business avoid business logic abuse. You can get started free with an API security assessment, or contact us for a live demo.